body, html{
    height: 100%;
}
.content{
    position: relative;
    height: 100%;
    background: #f2f2f2;
    overflow: hidden;
}
.content .yudi{
    position: absolute;
    opacity: 0;
    animation: drops 1.2s cubic-bezier(0.43, 0.01, 0.2, 0.43)  infinite; /*动画效果*/
    /*红包样式*/
    width: 60px;
    height: 60px;
    background: url(../img/对联.png) no-repeat;/*红包小图片可到iconfont.cn下载*/
    background-size: auto 60px;
}
@keyframes drops{
    0%{
        opacity: 0;
    }
    20%{
        opacity: 1;
    }
    90%{
        opacity: 1;
    }
    100%{
        opacity: 0;
        transform: translate3d(10px,100vh,-10px);
    }
}
